Principal limitation of
cell therapy is cell loss after
transplantation because of the interplay between
ischemia,
inflammation, and apoptosis. We investigated the mechanism of preconditioning of mesenchymal stem cells (MSCs) with
oxytocin (OT), which has been proposed as a novel strategy for enhancing therapeutic potential of these cells in ischemic heart. In this study, we demonstrate that rat MSCs express binding sites for OT receptor and OT receptor transcript and
protein as detected by RT-PCR and immunofluorescence, respectively. In response to OT (10(-10) to 10(-6) M) treatment, MSCs respond with rapid
calcium mobilization and up-regulation of the protective
protein kinase B (PKB or Akt) and phospho-ERK1/2
proteins. In OT-stimulated cells, phospho-Akt accumulates intracellularly close to the mitochondrial marker
cytochrome c oxidase subunit 4. Functional analyses reveal the involvement of Akt/ERK1/2 pathways in cell proliferation, migration, and protection against the cytotoxic and apoptotic effects of
hypoxia and serum deprivation. In addition, OT preconditioning increases MSC
glucose uptake. Genes with angiogenic, antiapoptotic, and cardiac antiremodeling properties, such as
heat shock proteins (hsps) HSP27, HSP32, HSP70,
vascular endothelial growth factor,
thrombospondin,
tissue inhibitor of metalloproteinase (TIMP)-1,
TIMP-2,
TIMP-3, and
matrix metalloproteinase-2, were also up-regulated upon OT exposure. Moreover, coculture with OT-preconditioned MSC reduces apoptosis, as measured using terminal
transferase dUTP nick end labeling assay in newborn rat cardiomyocytes exposed to
hypoxia and reoxygenation. In conclusion, these results indicate that OT treatment evokes MSC protection through both intrinsic pathways and secretion of cytoprotective factors. Ex vivo cellular treatment with OT represents an attractive strategy aimed to maximize the
biological and functional properties of effector cells.